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Plant Focus

Quercus xjackiana acorns
The hybrid of Q. alba and Q. bicolor

European Oak Open Days 2019

Fourteen participants mustered in Yorkshire, UK, on June 17th to commence the 2019 European Oak Open Days, having found their way from Czech Republic, Belgium, France, Germany, the Netherlands, and even the UK. We had planned to be 20 (the suggested size limit for a group), but attrition of one sort or another reduced our numbers: finally, and surprisingly, there were only two hardy UK members. It would appear that nothing changes: John Grimshaw, polymath director of the Yorkshire Arboretum, overhearing me muttering about soft southerners confirmed in a belief that the Yorkshire icecap remains until June, informed me that Caesar’s Roman occupation troops referred similarly to their southern counterparts. But seriously, I would be grateful if our UK members could advise via tours@internationaloaksociety.org whether the lack of UK interest this year lay with distance, the month, the fact that the visits were during the week, that you were insufficiently notified, or of course any other reason. Next year we hope to visit Wales . . . 

group thorp perow
The group at Thorp Perrow

It is considered a truism that if one wishes to have an Arboretum, one should inherit one. And yes, one would inherit impressive old trees, but as always in life there are possible downsides: they may be too close together; already in decline (and the dreaded honey fungus may be established); they may not be ideally placed in the landscape; and often there will be no record of their origin. On the other hand, a “clean sheet”, if boldly seized, can present a priceless opportunity for original landscaping with a well-documented planting, allowing experiment and subsequent research, but (downside again) less to one’s own advantage than that of one’s successors. Our visits this year allowed us to ponder both sides of this question. Thorp Perrow is an arboretum which has remained in one family for several generations, giving it a unique and almost tangible “atmosphere”; the Yorkshire Arboretum, although on a long-established estate, has been planted since 1979 on what was originally medieval parkland. And the conclusion? For me at least, I wouldn’t want to choose—both arboreta are necessary and complementary, both contributing greatly to the present and future arboreal richness of the British Isles.

Thorp Perrow
A vista in Thorp Perrow

The 100-acre Thorp Perrow Arboretum as we now see it was created by Colonel Sir Leonard Ropner, the grandfather of the present custodian, and contains five National Plant Collections in addition to 67 UK Champion Trees. However, the property can be traced back to the Domesday Book (the Norman property register completed in the year 1086). The 16th and 17th centuries saw the addition of many parkland trees (there is a “Catherine Parr” oak of 1535), and then fashionable plantings of North American imports were added in the mid-1800s to a section known as the Millbank Pinetum, and include a champion Sequoia sempervirens. Tree expert Alan Mitchell was excited by what he saw on a visit, and subsequently IOS member Lord Michael Heseltine encouraged the late Sir John Ropner to make additional plantings in the 1980s. So a rich history indeed, and the arboretum attracts 75,000 visitors a year. Upkeep depends largely on volunteers, guided by one full-time gardener.

Quercus frainetto listing
Quercus frainetto listing to starboard at Thorp Perrow

Curator Faith Douglas was our expert guide for a morning tour of the arboretum, and in the afternoon we were free to explore. She first explained the system of labeling: the “disappearing label” syndrome compelled them to develop their own arrangement where each plant has a plastic cow’s ear-tag with first a letter denoting the zone of the arboretum and then a specific number which can be checked against a catalogue available at the welcome desk. The Arboretum can be subject to drought due to the uneven annual distribution of rainfall. Alkaline soil near the entrance and tearoom becomes heavy clay further out in the arboretum, and one area where 89 of a total of 90 poplars were removed was the next week full of water!

Quercus acherdophylla
Quercus acherdophylla, Thorp Perrow

The cool summers do not favor North American white oaks (and the same applies at the Yorkshire Arboretum, with a July mean of only 15.6 °C), but some other oaks have become enormous, such as a Q. rubra and a Cerris-section Q. libani which cast shade over most of the oak planting: other notable oaks include Q. trojana, Q. macranthera, Q. canariensis, and Q. faginea, some of which are now providing doughty competition for one another. Interestingly Q. kelloggii, which can be difficult to establish in Europe, seems to find an amenable home in Yorkshire: there is a good specimen here, and we were also to see a healthy (albeit younger) specimen at the Yorkshire Arboretum. Mexican oaks include Q. acherdophylla and of course the redoubtable Q. rysophylla. Oaks are also commemorative: there is a 1935 Q. robur sown in situ for the jubilee of King George V, a Red Oak avenue, and finally, on a mound, a notable “acorn” (yet to sprout) in honor of Sir John Ropner’s 70th birthday (see photo).

The yet-to-sprout acorn planted to mark Sir John Ropner's 70th birthday, with Cécile Souquet-Basiège for scale

The following day we reconvened at the Yorkshire Arboretum, around 40 miles east of Thorp Perrow, to be met by Director John Grimshaw and his Collections Manager Jonathan Burton. Over coffee, John first introduced us to the Arboretum, which is an enormous 124 acres, stretched in an east/west direction, and with wet clay to the south and a sandier soil to the north which includes a “Mediterranean” planting. It lies on the estate of Castle Howard (a 1699 renaming of an older medieval property).

Quercus podaim
Some participants with Quercus Pondaim Group at the Yorkshire Arboretum

Some old Q. robur survive from the mid-18th century, a veteran Q. petraea has a circumference of 4.89 meters, and there are clumps of oaks relating to the coronation of Queen Elizabeth II (1953), but the Arboretum plantings commenced in 1979 with 6,000 trees, mainly from the Hillier Nursery.

Quercus robur Timuki
Quercus robur 'Timuki', Yorkshire Arboretum

The oak list thus contains interesting named forms, in addition to the later wild-origin plantings of the 1980s. In contrast to the haphazard growth of many arboreta, planting was to a design by James Russell, and he remained involved during subsequent additions until the early 90s. The design includes wide open glades, and long vistas which cunningly curve at the end or disappear due to the terrain, often giving the visual impression that the Arboretum is limitless. The glades now include wildflower hay-meadows.

Quercus petraea Mespilifolia
Quercus petraea 'Mespilifolia', Yorkshire Arboretum

Development continues unabated—a Woodland Garden has been established since John’s tenure, and the hum of machinery during our visit announced that some of the main paths are being given a hard surface, which can make a positive difference to visitor numbers in a somewhat soggy climate (31,000 visitors last year).

Quercus semecarpifolia
Quercus semecarpifolia, Yorkshire Arboretum

A fuller coverage of both arboreta will appear in the next edition of the IOS journal, International Oaks.

A large proportion of our group headed east to the port of Hull to catch ferries back to the Netherlands, but some whose route home took them via Manchester airport were able to take advantage of Lloyd and Sally Kenyon’s generous offer to open their oak collection on the following day.

Group photo
Participants in the UK Oak Open Days 2019 with John Grimshaw and Jonathan Burton

Photos © Shaun Haddock